Preparation of sulphuric acid starch composition



Patente'd M ay 1 5, 1923.1

I a new WILLIAM HENRY scores, or covimr'am ENGLAND, .assreuoa 'ro coua'raunns Y 1 LIMITED, or LONDON, ENGLAND.

PREPARATION OF SULPHURIC ACID STARCH COMFOSITION. i

No Drawing.

To all whomitvnag concern:

Be it known that I, TVILLIA HENRY STOKES, a subject of the King of Great Brit- 10 with fairly concentrated. sulphuric acid (containing say 60 per cent H SO,,)' the starch gelatinizes and-forms lumps, which, cannot, or only with great difficul ty can, be

mixed with the sulphuric -acid, so as to yield a homogeneous mixture. Such mixture, preferably diluted .with water, may be used toladvantage in the preparation'of, or as an addition to, a setting bath for usev in the manufacture of .threads, filaments, strips,

films, etc., from viscose, as mentioned in the copending application of M. T. Callimachi, Ser. No. 548,477 filed herewith, patented March 27 1923 under .No. 1,449,380.

Accordingto the present invention this difiiculty is overcome bymixing the starch, or. starchy matter, in a-finely-div'ided condition, with sulphuric acid of such dilution and, at such moderate temperature, that no I gelatinization takes place, and then pouring 30 rapidly into themixture thus obtained, and

whilst stirring, suflicient concentrated sulphuric acid tobringthe mixture to'the desired concentration. The solution thickens at first, but in a very short time, becomes thin and, on continued stirring, is "obtained in a good homogeneous condition. The concentrated sulphuric acid is to be added rapidly, so that at any rate by far the greater part thereof has been introduced before the 40 able extent. If the said concentrated acid 4 be'run in slowly, local thicken-ing'takes place to such a degree that it is no longer pomibleto stir the mass. The total quantity of acid used should be at least about 75 parts-by weight of pure sulphuric acid to every 100 parts by weight of starch.

As a general rule, the temperature of the mixture, during the addition of the concento rise considerably, forinstance, it-should not be allowed to rise above a temperature at which charring of the organic material is likely to occur. It is preferred to cool the whole mass during the mixing, and this coolthickening has proceeded to any consider trated sulphuric acid, should notbe allowed Application-filed March 3-1, 1922. semi meme;

mg may be effected, for instance, by meansof cold water. passing through, coils in the mixing ves el.

The concentrations of'the two quantities of sulphuric'aciid,-.that is to say, the more "dilute portion, and the more concentrated portion, can be varied within fairly wide limits, without departing from the nature of. this invention, "provided that the mixture of the starch,- or the. like, with the more dilute portion of sulphuric acid is obtained without gelatinization and formatlon' of lumps, and thatthe addition of the more :concentrated portion-of sulphuric acid takes place withsuflicien't rapidity and whilst avoiding too great a rise of temperature.

acid, thegrea'ter will'be the amount of heat developed on running it into the said re liminary mixture. lso, the more' di ute portion of sulphuric acid, used for admixture with the starch, or the like, should pref erably not be chosen. too dilute, since the Forinstance, it-is-not advisable to employ sulphuric acid offtoojhigh a concentration subsequent addition of the more concentrated portion of sulphuric acid will. give rise to a higher temperature, in accordance with the amount of water contained in the said dilute portion of sulphuric acid. For this'reason it is generall preferred'toemploy dilute sulphuric aci of a strength appreaching 30% by weight.

The following isan example of the. man-- her in which this invention may be performed, but the invention is not limited to this example- The parts are 1) weight.

Add fourteen-parts of powered starch,- or starchy matter, to fifteen parts of sulphuric acid, containing 28 per cent 11 60,, stirring the mixture well, and maintaining it at a temperature of about 28 to 30 centigrade. .A finepaste of a creamy consistency is obtained. Then allow fourteen parts-of sul huric acid (containing 77 per cent H,,O,) 'to flow in rapidly, the time taken for the addition being, say, one minute, or less. The stirring and cooling should be carried on continuously. The whole mixture becomes very thick, but, after two, or three, minutes, it commences to liquefy. After continued stirring for a few hours, a clear homogeneous liquid is obtained.

' Although I have referred to th e'use of the product for the setting bath used in making artificial silk and the like from viscose, it is V to be understood that the product is not limited to this use, but may be employed starch .in a sense broad enough to include any starchy matte r which can beadvantageously treated in accordance withthe' invention.

"What I claim is with sulphuric acid of such dilution, and at such moderate temperature,'that no gelatinization takes place, and then rapidly adding,

whilststirring, a I uantity of concentrated sulphuric acid su cient ,to yield,' on' eon- .tinued stirring, a homogeneous product of thedesired concentration. 2. The process of making mixtures'of 1 starch and sulphuricacid, consisting in mixa v ing thestarch, in a finely powdered condi tion, with :dilute sulphuric acid'containing about 28 per cent of H 80 and at a temperature'f of about from 20 to centiand continuing stirring andfcooling until a clear homogeneous product has "been: ob-

tained.

3. The process of making mixtures of starch and sulphuric acid,-consisting in mixing the-starch, ina-finely divided condition, with; dilute sulphuric acid containing from a about 20 to 30*per cent of H 80 at a tem- 1. The process of makingmixtures 'of starch and sulphuric acid, consisting in mixing the starch, in a finely divided condition,

Sperature not exceeding 30 centigrade, and then adding, as rapidly as possible, and

whilst stirring, a quantity of concentrated 3 sulphuric acid containingv at least per cent H suflicientto cause the yield of'a clear homogeneous product eontainin not less than. 75' parts by weight oflsulp uric acid to every parts by weightof starch.

In' testimony whereof I- have signed my name to'this specification in the'presenceof two subscribin' witnesses; .WILL IAM HENRY "Witn'essesfl 'Hoimon JAMESHEGAN,

Jon-N ALEXANDER Lnoirn.

STOKES. 

